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Over the last 2 decades, routine collections in the Hawaiian Archipelago have expanded to mesophotic reefs, leading to the discovery of a new red algal genus and species, here described as Anunuuluaehu liula gen. et sp. nov. This study provides a detailed genus and species description and characterizes chloroplast and mitochondrial organellar genomes. The new genus, Anunuuluaehu, shares many characteristics with the family Phyllophoraceae and shows close similarities to Archestennogramma and Stenogramma, including habit morphology, nemathecia forming proliferations at the outer cortex with terminal chains of tetrasporangia, and carposporophytes with multi‐layered pericarps. The single species in this genus exhibits distinctive features within the Phyllophoraceae: the presence of single‐layer construction of large medullary cells and the development of long, tubular gonimoblastic filaments. Multi‐gene phylogenetic analyses confirmed it as a unique, monophyletic lineage within the family. Cis‐splicing genes, interrupted by intron‐encoded proteins within group II introns, are present in both the chloroplast and mitochondrial genomes of A. liula. Notably, a specific region of the coxI group II intron exhibits similarity to fungal introns. Anunuuluaehu liula is presumed to be endemic to the Hawaiian Archipelago and thus far is known to live solely at mesophotic depths from Hōlanikū to Kaho'olawe ranging from 54 to 201 m, which is the deepest collection record of any representative in the family. Overall, this study enhances our understanding of the genomic and taxonomic complexities of red algae in mesophotic habitats, emphasizing the significance of continued research in this area to uncover further insights into evolutionary processes and biogeographic patterns. [ABSTRACT FROM AUTHOR]

The Papahānaumokuākea Marine National Monument, Hawai'i, is one of the most isolated and protected archipelagos in the world, making it a natural laboratory to examine macroalgal-microbial diversity because of limited direct anthropogenic impacts. We collected the most abundant macroalgae from nine sites ranging from shallow subtidal (1.5 m) to mesophotic (75 m) depths around Manawai (Pearl and Hermes Atoll). We characterized the macroalgal bacterial communities via high-throughput amplicon sequencing and compared the influence of host phylum, species, site, and depth on these relationships at a single atoll. Ochrophyta species had the lowest bacterial diversity compared to Chlorophyta and Rhodophyta. Site and/or depth may influence the microbial community structure associated with Microdictyon setchellianum, indicating a possible disconnect of these microbial communities among habitats. Chondria tumulosa, a cryptogenic species with invasive traits, differed in associated microbiota compared to the native Laurencia galtsoffii, an alga from the same family collected at the same site and depth. While there was overlap of bacterial communities across sites for some algal species, the majority had minimal macroalgal-microbial community connectivity across Manawai. This mesophotic system, therefore, did not appear to be refugia for shallow water coral reefs at microscopic scales. Additional studies are required to identify other significant influences on microbial community variation. [ABSTRACT FROM AUTHOR]

Two genera of the Rhodymeniales, Halopeltis and Leptofauchea, are here reported for the first time from the Hawaiian Islands and represent the deepest records for both genera. Molecular phylogenetic analyses of cytochrome oxidase subunit I (COI), rbcL, and large subunit ribosomal DNA (LSU) sequences for Hawaiian specimens of Leptofauchea revealed one well-supported clade of Hawaiian specimens and three additional lineages. One of these clades is described here as Leptofauchea huawelau sp. nov., and is thus far known only from mesophotic depths at Penguin Bank in the Main Hawaiian Islands. L. huawelau sp. nov. is up to 21 cm, and is the largest known species. An additional lineage identified in the LSU and rbcL analyses corresponds to the recently described L. lucida from Western Australia, and is a new record for Hawai'i. Hawaiian Halopeltis formed a well-supported clade along with H. adnata from Korea, the recently described H. tanakae from mesophotic depths in Japan, and H. willisii from North Carolina, and is here described as Halopeltis nuahilihilia sp. nov. H. nuahilihilia sp. nov. has a distinctive morphology of narrow vegetative axes that harbor constrictions along their length. The current distribution of H. nuahilihilia includes mesophotic depths around W. Maui, W. Moloka'i, and the island of Hawai'i in the Main Hawaiian Islands. Few reproductive characters were observed because of the small number of specimens available; however, both species are distinct based on phylogeny and morphology. These descriptions further emphasize the Hawaiian mesophotic zone as a location harboring many undescribed species of marine macroalgae. [ABSTRACT FROM AUTHOR]

Molecular phylogenetic analyses of Hawaiian members of the red algal family Dumontiaceae were used to clarify the species diversity of Dudresnaya and Gibsmithia from Hawaiʻi. Although no new species of Dudresnaya were detected in the analyses, D. babbittiana is newly recorded by Lalo, Manawai, and Oʻahu; however, this record remains tentative until the type material is sequenced. A new species of Gibsmithia, G. punonomaewa A.R. Sherwood, is described here and reported from the mesophotic depths (79–104 m) of the Papahānaumokuākea Marine National Monument, Hawaiʻi. This new species differs from all others in the genus based on the following combination of characters: moderate thallus size (up to 11 cm), smooth and terete gelatinous lobes, presence of a stipe (which is often branched), globose carposporangia, and a non-isodiametric shaped cell subtending the tetrasporangia. This new taxon increases the number of Gibsmithia species recorded from Hawaiʻi to three. Phylogenetically, G. punonomaewa is most closely related to G. dotyi (type locality, Lord Howe Island, Australia) and G. larkumii (type locality, One Tree Island, Queensland, Australia), which are both reportedly widespread in distribution. The relatively dark habitat of the mesophotic in Papahānaumokuākea Marine National Monument contrasts with the surface waters of tropical and subtropical habitats where most Gibsmithia species are found, further highlighting the uniqueness of the species. [ABSTRACT FROM AUTHOR]

The calcified encrusting brown algal genus Newhousia is reported from three new archipelagos in the Pacific: (1) Society Islands, French Polynesia; (2) Guam, Mariana Islands; and (3) Vanuatu. Newhousia presents a simple morphology consisting of small, rounded, two-layered calcified blades with limited interspecific variability in morphological features. Consequently, resolving cryptic diversity in Newhousia requires molecular phylogenetics. Bayesian and maximum likelihood phylogenetic trees, based on the concatenated cox1, cox3, psbA, rbcL and 18S rDNA sequences, supported a sister relationship of Newhousia with Lobophora/Zonaria clade. Analyses revealed five distinct evolutionary lineages within Newhousia. Genetic variation between the lineage from Guam and the two hitherto known Newhousia species, N. imbricata from Hawaii and N. yagha from Papua New Guinea, warrant the description of one new species, N. sumayensis sp. nov. The other two lineages, from the Society Islands and Vanuatu, were identified as geographically distinct populations of N. imbricata with limited genetic variation, rather than independent species. In the Society Islands, N. imbricata is common between depths of 10 m and 20 m as unattached spherical structures, or attached to hard substrate. In Guam, N. sumayensis sp. nov. grows abundantly in sciophilous habitats at depths of 10–21 m. We provide the first documentation of spores for this genus and of structures resembling plurilocular antheridia. Increased sampling throughout the Indo-Pacific region is required to further elucidate the distribution range and patterns of species richness in Newhousia. [ABSTRACT FROM AUTHOR]

A new species of mesophotic marine red algae, Ethelia hawaiiensis sp. nov., is illustrated and described. Ethelia hawaiiensis is distinguished from other members of the genus by its large diameter assurgent filament cells, and in having thallus cavities that are frequently inhabited by microalgae, as well as in DNA sequence. Analyses of mitochondrial COI, plastid rbcL, and nuclear SSU sequences demonstrated that E. hawaiiensis was distinct from other species of Ethelia and that it was not phylogenetically closely related to other known species. Both COI and rbcL analyses placed E. hawaiiensis within a clade of other Ethelia sequences, while the SSU analyses, which only included two previously described species of Ethelia, resolved E. hawaiiensis as sister to a clade comprising Ethelia plus the Peyssonneliales. Morphological differences between E. hawaiiensis and other members of the genus are discussed. [ABSTRACT FROM AUTHOR]

Haraldiophyllum hawaiiense sp. nov. is described as a new mesophotic alga and a new genus record for the Hawaiian Islands. Six specimens were collected at a depth range of 81-93 m from Papahānaumokuākea Marine National Monument, and their morphology investigated, as well as molecular phylogenetic analyses of the plastidial ribulose-1,5- bisphosphate carboxylase--oxygenase large-subunit (rbcL) gene and a concatenated alignment of rbcL and nuclear large-subunit rRNA gene (LSU) sequences. Phylogenetic analyses supported H. hawaiiense sp. nov. as a distinct lineage within the genus Haraldiophyllum, and sister to a large clade containing the type species, H. bonnemaisonii, as well as H. crispatum and an undescribed European specimen. The six Hawaiian specimens were shown to be identical, but unique among other species of the genus as well as the recently segregated genus Neoharaldiophyllum, which comprises half of the species previously included in Haraldiophyllum. The vegetative morphology of H. hawaiiense sp. nov. resembles Neoharaldiophyllum udoense (formerly H. udoensis); however, no female or post-fertilization structures were found in the Hawaiian specimens to allow a more comprehensive comparison. The molecular phylogenies demonstrate that Haraldiophyllum is paraphyletic, suggesting either that the Myriogrammeae tribe includes undescribed genera, including Haraldiophyllum sensu stricto, or that Neoharaldiophyllum species should be transferred into the genus Haraldiophyllum. However, based on vegetative morphology and molecular analyses, and pending resolution of this taxonomic issue, the Hawaiian specimens are placed within the genus Haraldiophyllum. This new record for the Hawaiian Islands highlights the novel biodiversity from mesophotic depths, reaffirming the need for further investigation into the biodiversity of Mesophotic Coral Ecosystems. [ABSTRACT FROM AUTHOR]

Survey cruises by the National Oceanic and Atmospheric Administration (NOAA) in 2016 and 2019 yielded specimens of an undetermined red alga that rapidly attained alarming levels of benthic coverage at Pearl and Hermes Atoll, Papahānaumokuākea Marine National Monument, Hawaiʻi. By 2019 the seaweed had covered large expanses on the northeast side of the atoll with mat-like, extensive growth of entangled thalli. Specimens were analyzed using light microscopy and molecular analysis, and were compared to morphological descriptions in the literature for closely related taxa. Light microscopy demonstrated that the specimens likely belonged to the rhodomelacean genus Chondria, yet comparisons to taxonomic literature revealed no morphological match. DNA sequence analyses of the mitochondrial COI barcode marker, the plastidial rbcL gene, and the nuclear SSU gene confirmed its genus-level placement and demonstrated that this alga was unique compared to all other available sequences. Based on these data, this cryptogenic seaweed is here proposed as a new species: Chondria tumulosa A.R.Sherwood & J.M.Huisman sp. nov. Chondria tumulosa is distinct from all other species of Chondria based on its large, robust thalli, a mat-forming tendency, large axial diameter in mature branches (which decreases in diameter with subsequent orders of branching), terete axes, and bluntly rounded apices. Although C. tumulosa does not meet the criteria for the definition of an invasive species given that it has not been confirmed as introduced to Pearl and Hermes Atoll, this seaweed is not closely related to any known Hawaiian native species and is of particular concern given its sudden appearance and rapid increase in abundance in the Papahānaumokuākea Marine National Monument; an uninhabited, remote, and pristine island chain to the northwest of the Main Hawaiian Islands. [ABSTRACT FROM AUTHOR]

Specimens of red algae corresponding to the peyssonnelioid genus Sonderophycus were collected at Kure Atoll, Hawai'i, at a depth range of 88-94 m depth during mesophotic surveys of the Papahānaumokuākea Marine National Monument, Hawaiian Islands, and were analyzed using morphological and molecular approaches. Analyses of mitochondrial cytochrome oxidase subunit 1 and chloroplast rbcL DNA sequences demonstrated that the Hawaiian specimens were identical to one another yet distinct from the three other species currently recognized within the genus (S. capensis [Montagne] M. J. Wynne, S. coriaceus [Womersley & Sinkora] M. J. Wynne, and S. fervens Dixon), as well as the likely congener, Peyssonnelia caulifera Okamura, and are proposed here as a new species: Sonderophycus copusii A. R. Sherwood. Sonderophycus copusii is morphologically distinct from other members of the genus by the following combination of characters: the presence of occasional secondary perithallial growth, emergence of rhizoids from the hypobasal cuticle at a strongly acute angle, a lack of horizontally directed filaments in the lower perithallus, and the lack of a stipe. This is the first record of the genus Sonderophycus in the Hawaiian Islands. Sonderophycus copusii was documented as a dominant member of the algal community at Kure Atoll, and thus may play a significant ecological role in the deep-water benthic community of Kure Atoll, along the lines of reports of deep water peyssonnelioid beds in the Mediterranean, Red Sea, and Caribbean. This study further highlights the unexplored diversity of the Peyssonneliales in Hawai'i, and emphasizes more generally the degree of as yet undiscovered biodiversity of algae at mesophotic depths. [ABSTRACT FROM AUTHOR]

The complete chloroplast genome of Chondria tumulosa, a red alga from Manawai (Pearl and Hermes Atoll), Hawai'i, was determined and analyzed using next-generation sequencing and de novo assembly approaches. The chloroplast genome sequence of C. tumulosa was 172,617 bp and contained 231 genes, consisting of 197 protein-coding genes, 29 transfer RNA genes, three ribosomal RNA genes, one transfer-messenger RNA gene, one non-coding RNA gene, and one intron inserted into the trnM gene. The number of genes and genome structure was largely similar to other members of the family Rhodomelaceae. The phylogenomic analysis of 32 complete cpDNA from the red algal order Ceramiales showed that C. tumulosa is a distinct species within the Chondrieae tribe, and is a diverging early relative to the other three available Chondria chloroplast genomes. [ABSTRACT FROM AUTHOR]

To resolve the paraphyly of Batrachospermum, the sections of the genus have been methodically investigated using DNA sequence data and morphology; this has resulted in the raising of many sections to genus status. Phylogenetic analyses of combined rbcL and COI-5P showed Batrachospermum section Macrospora to be a well-supported clade. We propose Montagnia gen. nov. Montagnia is distinguished from other sections or genera of the Batrachospermales by the following characters: plants irregularly branched; carpogonial branches long and straight and well differentiated from fascicles, bearing involucral filaments in a crown pattern; enlarged pit connections in the cells of carpogonial branches; and pedunculate carposporophytes with large carposporangia. Within the new genus, we re-evaluated the characters used to circumscribe species by examining type specimens as well as samples from North and South America. Of the three currently accepted species attributable to Montagnia, we recognised two species: M. macrospora–type species (proposed synonyms Batrachospermum equisetifolium, B. hypogynum and B. macrosporum) and M. australis (synonym Batrachospermum australe). Morphological characters did not distinguish the two species due to variation within and among samples. The two species can be differentiated only using DNA sequence data and geographic distribution. Montagnia australis is restricted to North America; whereas, M. macrospora is a widespread pantropical species occurring in South America and Asia. Although the intraspecific divergence observed in M. macrospora is the highest reported for members of Batrachospermales, species delimitation methods did not suggest that more than one species is justified. [ABSTRACT FROM AUTHOR]

Only two mitochondrial (mt) genomes had been reported in members of the red algal order Batrachospermales, which are confined to freshwater habitats. Additional mt genomes of six representative members (Batrachospermum macrosporum, Kumanoa ambigua, K. mahlacensis, Paralemanea sp., Sheathia arcuata, and Sirodotia delicatula) were sequenced aiming to gain insights on the evolution of their mt genomes from a comparative analysis with other red algal groups. Mt genomes sequenced had the following characteristics: lengths ranging between 24,864 nt and 29,785 nt, 22 to 26 protein-coding genes, G + C contents of 21.3 to 30.7%, number of tRNA of 16 to 37, non-coding DNA from 3.8% to 14.8%. Comparative analysis revealed that mt genomes in Batrachospermales are highly conserved in terms of genome size and gene content and synteny. Phylogenetic analyses based on COI nucleotide data revealed high bootstrap support only for the genera usually recovered in the phylogenetic analyses but no support for supra-generic groups. The insertion of a group II intron carrying an ORF coding for the corresponding intron maturase interrupting the COI gene was observed in Paralamenea sp. and accounted for its larger genome in comparison to the other Batrachospermales mt genomes. [ABSTRACT FROM AUTHOR]

Chroothece has been reported from a range of freshwater environments, including streams, shallow ponds, trickling water on cliffs and moist soils, mostly in Europe and North America. The identification of genera and species by morphology is difficult because of overlaps in critical characters. To help clarify diversity within the genus, samples from Spain and from other regions (UK and Guam, western Pacific) were compared. Ecological and morphological data from field and cultured material were correlated with molecular data (rbcL gene sequences) that differentiate two new species: Chroothece thermalis I. Chapuis, P. Sánchez, M. Aboal & O. Necchi Jr., sp. nov. in a thermal spring and Chroothece lobata M. Aboal, B. A. Whitton, I. Chapuis, P. Sánchez & O. Necchi Jr., sp. nov. in a semi-arid stream. The results suggest recognition of four species, C. thermalis, C. lobata, C. richteriana Hansgirg and C. rupestris Hansgirg, from Spain. Morphology and ecology are useful to help distinguish these species, but the genus needs further study for possible cryptic diversity. [ABSTRACT FROM AUTHOR]

Phylogeography of Setacea puiggariana, which is widely distributed in southern and south-eastern Brazil, with few records in South America and Africa, was investigated based on mitochondrial genetic markers: the cox2-3 spacer and the barcode region of cox1 gene. Ten stream segments were sampled across the known geographic distribution in Brazil, with a total of 65 individuals sequenced for the cox2-3 spacer and 30 for cox1. Six cox2-3 and eight cox1 haplotypes were observed among the individuals analyzed. Two haplotypes were found in one location for cox2-3 spacer, with all other locations having just one haplotype. Each of the cox1 haplotypes was found in a distinct location. Haplotype networks showed one haplotype occurring in most locations in southern and south-eastern Brazil for cox2-3 and revealed a relatively complex structure for cox1, with the same haplotype represented by individuals from two distant locations of southern and south-eastern Brazil. The low divergence observed among the Brazilian haplotypes supported the recognition of all collections as a single species, for both markers considering the geographic range sampled (maximum distance ∼ 1000 km) as compared with previous studies at similar or broader geographic scales (> 2500 km). This study confirmed the general pattern found in Batrachospermales: that little variation is typically observed within a location and that most populations have one, rarely two haplotypes. In addition, we found no evidence of higher genetic divergences with increased geographic distance among haplotypes, which has also been reported in members of the Batrachospermales. [ABSTRACT FROM AUTHOR]

SUMMARY Phylogeography of B atrachospermum viride-brasiliense was investigated using two mitochondrial regions: the cox2-3 spacer and the barcode region of cox1 gene. Eighty-seven individuals were analyzed from nine stream segments throughout its distribution in Brazil. Ten cox2-3 spacer and nine cox1 haplotypes were observed among the individuals studied (87 vs. 43, respectively). Divergences among haplotypes were relatively low (≤2.4% for cox2-3 and ≤1.8% for cox1). Most locations have a single haplotype, whereas only two locations had two haplotypes for both markers. The haplotype network for cox2-3 showed a phylogeographic trend from the south towards the southeast with haplotypes from the southeast more closely related. For cox1 a trend from the southeast spreading towards the south and north was revealed, with the southern haplotypes more closely associated. Results clearly indicated that B . viride-brasiliense represents a single species and the phylogeographic pattern consisted of a closely connected group of haplotypes from southern and southeastern Brazil. Levels of intra- and inter-population variation were similar for the two markers with slightly higher values for cox2-3. The trend observed in this study is similar to that in other members of Batrachospermales with little variation within a stream segment (one or two haplotypes) and more distant haplotypes showing higher divergences. This pattern could be attributed to the fact that colonization of a site might be rare by a single event with subsequent proliferation of the population. The geographic distribution of B . viride-brasiliense was interpreted according to the biogeographic models proposed for South America being limited to three morpho-climatic domains or biogeographic provinces: tropical Atlantic rainforest, sub-tropical rainforest and cerrado ( Brazilian savannah). [ABSTRACT FROM AUTHOR]

Thorea indica sp. nov. is described from the Sai River, Uttar Pradesh, India (26°39'00.7" N, 80°47'38.3" E). Its classification is based on molecular sequences of the plastid-encoded RuBisCO large-subunit gene, rbcL and the barcode region of the mitochondrial encoded cytochrome c oxidase subunit 1, cox1, and morphological data. The sequence analyses confirm a new species of Thorea. The cox1 barcode sequence had 90.4-90.8% identity with Thorea sp. from Australia and Thorea hispida from Hawaii and China. Based on rbcL sequences the Indian specimen was positioned in a major clade with high support (>95 bootstrap and 0.95 posterior probability) containing two other species: T. okadae from Japan and T. hispida from the continental USA, Hawaii, the UK, and China. The divergences among these sequences were T. indica vs. T. okadae (2.8%) and T. indica vs. T. hispida (2.9-3.4%). The comparison of morphological characters of Thorea from India was not conclusive due to the inadequate descriptions in previous reports: most specimens reported as T. hispida fit within the circumscription of T. indica as described here. The previous report of T. siamensis from the Sai River is incorrect and the specimens fit within our description of T. indica. Thorea indica and T. okadae can be distinguished by minor morphometric characters and sexuality (dioecious vs. monoecious). [ABSTRACT FROM AUTHOR]

Considering the lack of knowledge on genetic variation on members of the freshwater red algal of the order Batrachospermales in tropical regions, phylogeographic patterns in Sirodotia populations were investigated using two mitochondrial regions: the cox2-3 spacer and partial cox1 gene (barcode). Individuals identified as Sirodotia delicatula were analyzed from 14 stream segments across its distribution in Brazil. Phylogenetic analyses based on the ribulose-1,5-bisphosphate carboxylase/oxygenase large sub-unit gene showed three clades, one representing S. delicatula, from all locations in southeastern Brazil and other regions from Brazil. The remaining samples formed two clades, which were highly divergent and distantly positioned from those of S. delicatula: 2.5-2.7% and 3.4-3.7%. This level of variation would warrant the species split of these taxa from mid-western Brazil. A total of eight cox2-3 spacer and nine cox1 haplotypes were observed among the 122 individuals studied. One location had two cox2-3 haplotypes and three locations had two cox1 haplotypes; all others had a single dominant haplotype each. The existence of high intraspecific genetic variation among individuals of distinct locations (several haplotypes), but little variation within a location seems to be a pattern for the Batrachospermales. Haplotype networks showed low variation among the haplotypes from southeastern Brazil (10 locations with divergence of 0.3-1.1% for cox2-3, 0.1-0.3% for cox1) and high variation among the haplotypes from the mid-west region (four locations, 4.0-9.3% for cox2-3, 6.2-8.4% for cox1). Thus, the present data clearly suggest the existence of cryptic species in Sirodotia in Brazil. [ABSTRACT FROM AUTHOR]